gnu: Add postgresql-11.

* gnu/packages/databases.scm(postgresql-11): New variable.

gnu/packages/databases.scm

@@ -35,6 +35,7 @@
 ;;; Copyright © 2018 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;; Copyright © 2019 Jack Hill <jackhill@jackhill.us>
 ;;; Copyright © 2019 Alex Griffin <a@ajgrf.com>
+;;; Copyright © 2019 Gábor Boskovits <boskovits@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -846,6 +847,19 @@ TIMESTAMP.  It also supports storage of binary large objects, including
 pictures, sounds, or video.")
     (license (license:x11-style "file://COPYRIGHT"))))
 
+(define-public postgresql-11
+  (package
+    (inherit postgresql)
+    (name "postgresql")
+    (version "11.4")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "https://ftp.postgresql.org/pub/source/v"
+                                  version "/postgresql-" version ".tar.bz2"))
+              (sha256
+               (base32
+                "12ycjlqncijgmd5z078ybwda8ilas96lc7nxxmdq140mzpgjv002"))))))
+
 (define-public postgresql-9.6
   (package
     (inherit postgresql)